Testing apparatus



' May 2 1940. w s PRAEG 2,202,638

TESTING APPARATUS Filed April 17, 1939 4 Sheets-Sheet 1 INVENTOR.

WALTER $.PRAEG AT ORNEYS May 28, 1940. w. s. PRAEG TESTING APPARATUSFiled 'Apri1 17, 1939 4Sheets-Sheet 2 INVENTOR.

WALTER S. PRAEG f ATTORNEY May 28, 1940.

W. S. PRAEG TESTING APPARATUS Filed A ril 17, 1959 4 sheets sheet 5 FIG. 6. I

. I INVENTOR. WALTER s. PRAEG 414%. M2 MM ATTORNEYS 4' Sheets-Sheet 4 w.s. PRAEG TESTING APPARATUS Filed April 17, 1959 May 2 8, 1940.

( INVENTOR. WALTER S. PRAEG Y 4 WMgt ATTORNEY Patented May 28 1940UNITED STATES TESTING APPARATUS Walter S. Praeg,

Detroit, Mich., assignor to National Broach & Machine Company, Detroit,

Mich., a corporation of Michigan Application April 17, 1939, Serial No.268,413

17 Claims.

2 The present invention relates to testing apparatus and moreparticularly to a lead checker adapted to accurately measure the lead ongears and the amount of crowning on gears.

, The manufacture of gears with cut teeth has developed in the lastfifteen years from an entire dependence upon the machine operator to acoordination of effort on the part of the operator and the men in a gearlaboratory; this laboratory being equipped with the most sensitivemeasuring equipment available for measuring elements of gear teeth. Inall gears it is necessary that the teeth bear a proper relationship tothe axis of the gear. 111' spur gears the teeth must be paralleled inall planes with the axis of the gear. In helical or spiral gears theteeth must have a uniform helical advance around the axis of the gear,one

complete revolution of helical advance being known as the lead of thegear. The angular relationship of the pitch line on the gear to its axisis known as its helix angle.

A number of different designs of lead measurring machines are available,all of which are complicated in mechanism and slow to set up and 25operate. This does notofier any serious difficulty when only onepiece-is to be measured. When it is necessary to measure leads on anumber of pieces the time consumed to do this work becomes a seriousfactor. 30 A very satisfactory way to measure lead is to check a leadagainst a known lead This is accomplished very simply by the apparatusdisclosed in the present application.

Briefly described, a master element, which may be in the form of a gearor a cylindrical element having one or more helical slots of known angleformed thereiniis mounted to be rotated with the gear to be tested. Amovable assembly com: prising a relatively fixedly mounted tip to engagethe master element and a movable tip to engage .a

elative translation between the master element and the gear on the onehand and the tips referred to on the other hand takes place, move- -mentof the movable tip indicates deviation between the angle of the toothbein measured and the corresponding surface of tge master element.

It is accordingly anobject ,of the present invention to provide ameasuring apparatus for measuring angles or crowning of gear teeth.-

It is a further object of the present invention to provide apparatus ofthe character described, characterized by its extreme simplicity and byits 55 efliciency and rapidity in operation.

It is a further object of the present .liivention 'to provide testingapparatus of the character described embodying numerous improvedelements of design. so Other objects of the invention will be apparenttooth of the gear being tested is provided. .As

as the description proceeds, and when taken 1 conjunction with theaccompanying drawings wherein:

Figure 1 is a perspective of my improved apparatus;

Figure 2 is an enlarged detail plan view showing the cooperatingelements;

Figure 3 is a fragmentary vertical section through the carriage of myapparatus;

. Figure 4is a section on the line 4-4, Figure 3; I Figure 4A. is asection on the line 4A-'4A,

- Figure 5 is a detail section of a contact element;

Figure 6 is an enlarged fragmentary section on the line 6-6, Figure 3;

Figure '7 is an enlarged fragmentary section on the line 1-1, Figure .3;

Figure 8 is a detailelevation of-a modification employed for testing agear provided with an integral shank;

Figure 9 is a side elevation partly in section of the structure shown inFigure 8; and

Figure 10 is a perspective of the master guidi'ng element.

Referring to Figure 1, the apparatus comprises a table in provided withways H along which are adjustably mounted in clamping relation a pair ofstocks l2 and I3 for receiving therebetween in rotatable relation amaster element l4 and agear or other article to be tested 15. Suitableclamping means indicated at l6 are provided, and in addition a-spindlelock nut I1 is carried by the stock l3. The master element l4 and thegear [5 are retained in non-rotatable relation on an arbor l0, which inturn is mounted for free rotation between the stocksl2 and I3.

Carried by the table Ill and adjustable thereon in ways I9 toward andawayfrom the spindle I8 is a pedestal 20 provided with suitable guidingways indicated generally at 2i. Mounted on the ways is a carriage 22which supports a contact member 23 carrying a contact element 24 adaptedto engage a toothof the guiding element M. Member 23 is adjustabletoward and away from the .master element and is adapted to be locked inadjusted position by a clamping screw or the like 25.

v The carriage 22 is provided, with ways 26 on which is mounted anindicator'support 2'I. The

indicatclr support is adjustable toward and away which in turn give adirect reading of the deviation between the angularity of the surfacebeing measured and the angularity of the corresponding surface of themaster element I4.

Referring now to Figures 4 and 4A, the pedestal is provided with lockingmeans comprising a shaft carrying a lock handle 4i and an eccentric 42whichinturn is associated with alocking pin 83 adaptedto actuate theclamp a4, movable in the ways I3 previously rei'erred to. The shaft 40is retained against axial movement by a lock screw movable in acircumferential groove 66. Thisarrangement provides formovement of thepedestal 20 bodily toward and away from the ways II and for rigidlyretaining the pedestal in adjusted position. The indicator support 21-,as shown in Figure 4, is movable toward and. away from the contactmember 23 along ways 25 and is adapted to be clamped in adjustedposition by means of a clamp 41 coop-' crating with a locking member 28.The indicator support 21 is provided with clamping means to carry a rod43 which supports the indicator mounting 30. The indicator support 21 isprovided with a rigidly supported guiding plate 49 bolted thereto andhaving a key movable in the ways 25. In addition a'second key 50 isbolted to the underside of the indicator support 21 and is provided witha pair of recesses 5| which receive compression springs 52. Theindicator support 21 is provided with a half-round recess 53"forreceiving the rod 48, and a second plate 54 is provided, also formed toprovide a half-round recess for the rod. Springs 52 urge the plate 54resiliently toward the indicator support and serve.

to clamp the rod 40 resiliently therebetween upon release of theclamping member 28. The spring compression is suflicient to preventaccidental rotation of the rod 48 with possible consequent damageto thesensitive indicator carried there'' by. When clamp 41 is tightened plate54 firmly locks rod 48 in adjusted position at the same time as it looksindicator support '21 in adjusted position in ways 26.

Referring now particularly to Figure 3, the

indicator support and mounting is shown in depivotal'ly supporting alever 59 which carries the measuring pointer 3| and the indicatoractuator 32. be freely supported with a constant force applied thereto,it is provided with a pair of spring pressed centers 60 and 6|, thespring being shown in Figure 7 and indicated at 52. The center 60 maybelocked in adjustedposition by a set screw 03," shown in Figure 3,centering bolts .64 being provided in the housing 51;

1 As shown in Figure 3, the indicator actuator 32 passes upwardlythroughthe central aperture referred to in the member 56 and clearance isprovided for movement of, the actuator 32. The member 55 is providedwith a pair of diametrically oppositely ergtending slotted ears to whichmay be bolted-indicators. 66, which may be of conventional design.

In order to provide foriiree movement the Preferably, in order that thislever shall carriage 22 the ways 2I comprise removable ball bearingraces I0 and a cooperating cage II containing ball bearings. The cage'isshorter than the races 10, as indicated in Figure 6, and stop platessuch as indicated at 13 are provided, with the result that the cage issubstantially self-centering.

Means are provided for translating the car- V riage 22 along thepedestal 20 and takes the form of a rack I5 bolted to the pedestal 20.The carriage 22 has mounted thereina pinion I6, shown' in Figure3,1which is in constant mesh with the rack I5. A handwheel 11 isprovided and is adapted to-rotate the gear 16' through suitablecooperating bevel gears indicated at 10. As

will be evident, rotation of the handwheel results in a relatively slowcontrolled translation of the carriage 22.

Referring now to Figure 5, I have illustrated in detail the arrangementof the contact member 23, which is slidably received in thecorrespondingly formed aperture in the carriage 22. The

member "23 may be clamped in adjusted position, as previously referredto, by the member 25.v

The contact element 24,;whichis adapted toengage the guiding surface ofthe master element I4, is integrally formed on ashort rod section 04and'is likewise slidable' in the bore of the tubular member 23. A flangeis formed thereon and is adapted to cooperate with a capmember'llithreadedly received on one end of the member 23. The relationship issuch that upon loosening the cap member 36 the contact element 24 may beadjusted toward or away from the master element I4 by a suitablerotation of the member 0|. The parts may be rigidly retained in adjustedposition by screwing the cap 86 inwardly while retaining member 8|against rotation. By this means the contact element 24 may be broughtinto predetermined relationwith the guide surface.

The mechanism just described is suitable for measuring gears which maybe mounted upon the arbor I8 either directly or by means of suitableconventional adapters. In the event-that the gear to be tested is formedintegrally with -a shaft, other provisions must be made. Mechanism fortaking care of this situation is illustrated in Figures 8 to 10.

In these figures .I have illustrated a head I 00 which is adjustabletoward and away from an oppositely disposed head. The :work piece isadapted to be supported for rotation between the i Z heads and to berigidly retained for rotation with a a-ma'ster' element I00. For thispurpose the-head I00 is provided with a. central bore I02 in which isreceived a centrally apertured block I03 adapted to begigidly clamped inthe bore I02 by means Offh cooperating nut I04, as clearly illustratedin Figure 9. Annular member I05 is mounted for'rotation relative to therelatively fixed block I03, appropriate ball-bearings indicated at I06and I0! being provided 'for this purpose. Master element adapted to beclamped in adjustedv position thereon by means of a clamping screw I03,or the liker Master element I08 is illustrated in detail in Figure 10and has. formed thereon one or more helical slots or grooves IIl which,as seen in this I! 10a s 'rotatably mounted on the annular .member I05andis'70 on the forward .face

with a set screw H'I which a driving connection rigidly secured to thegear ber I88. A plate H2 is bolted to the annular member I85, a rigidcenter H3 being formed orsecured on the forward. face of driving memberH4 is rotatably mounted plate H2 in adjusted position about by a setscrew H5. Formed of the annular 'member H4 are a pair of projections H6,each provided functions to receive being tested. I

In order to obtain a rigid assembly, an expanding adapter H8 is providedin the correspondingly formed central passage through the'block'l83. Theadapter H8, as indicated at-I I8, is slotted by a pair of diametricallyopposite slots extending completely through the adapter. The adapter H8is threaded as indicated at l28 iand as clearlyshown in Figure 9 thearrangement is such that the headed portion I2I of the adapter H8retains the relatively rotaryportions of the assembly in position. Alsoas shown in the figure, the headed portion I2l cooperates with thesuitably formed portion of the member I85 to form a race for the ballbearings I8'l. The adapter H8 is centrally a'pertured as indicated atI23, and this central aperture has a tapered portion I24 adapted tocooperate witha' wedging ball I25. A socket set screw I26, is threadedinto the passage I23, as indicated in Figure 9, and as will be ap-.parent is adapted to force the ball I against the conical surface I24.This ex ands. the adapter H8 at its slotted portion-and provides for anextremely rigid relationship between the .adapter H8 and the block I83.Preferably and as indicated in Figure 9, the adapter I I8 is providedwith a recess I21 formed to receive a screw driver, or the like, forassembly.

In this device as in the modification previously described, clampingmeans I28 are provided for clamping the head I88 in adjusted position inthe ways II.

From the foregoing detailed description the operation of my improvedconstruction willbe readily-apparent. The heads I3 and I2 or I88 may beadjusted along the ways II to accommodate any convenient length ofdevice to be tested within the limits of the machine. In a. like'mannerthe pedestal 28 may beadjusted toward and.

away from they ways II to accommodate any diameter of device tobe testedwithin the limits of the machine. In like manner the indicator support21 may be adjustedrelative to the carriag'e 22 to provide for anyconvenient spacing between the contact element 24 and the measuringpointer 3|. cator mounting may be relatively adjusted toward and awayfrom the device being measured or the master element'to accommodatedifferent diameter parts.

It will thus be seen that the device is extremely flexible and withinthe limits of the machine may be adjusted to take care of awide varietyof .parts.

Referring .more particularly to Figure &, it

will be notedthat in the preferred form a pair of the plate H2. A

and is adapted to be clamped thereto tozero.

'11 may take place with a corresponding slow In like manner both theindiv 38 and the contact member 23 means. By obtaining a suitablerelative adjustment between the master element I4 and the gear or otherelement being measured, it is possible to provide an initial contactbetween the indicator actuator 32 and either of the spring pressedelements 98. The spring which urges the element 88 into engagement withthe indicator actuator 32 also biases the lever 58 to retain themeasuring pointer 3| in contact with the surface being measured.

The parts may be adjusted to the position indicated and the indicatingpointer, if desired, set At this time rotation of the handwheeltranslation of the carriage 22 relative to the master element I4 and thework piece. If a helical element is being measured, and if the helicalslot on the master element is engaged by the contact element 24, it willbe apparent that this slow translation of the carriage 22 will I resultin a corresponding rotation of the master element I4. Since the masterelement I4 and the work piece, such as the gear I5, are rigidly mountedfor simultaneous rotation, rotation of the master element will result ina corresponding rotation of the work piece. As long as the helicalsurfaces under consideration are "inclined equally,

there will be no motion of the measuring pointer 3| and consequently nomovement of. the pointer on the dial of the corresponding indicator. If,however, there is a difference between the angularity of the two helicalsurfaces under con sideration, there will be a corresponding relativemovement of the measuring pointer 3| which will be transformed to .acorresponding indication on the dial of the indicator.- Having dueregard to the constants of the machine for any particular setting, thisreading of the indicator may translated directly into difference in an--'gularity of the helical surfaces or irregularities therein, and thelike:

Itis desired to emphasize at this time another important function of thepresent apparatus. As is well understood, itis common practice today toemploy crowned gears; that is, gears having teeth which arelongitudinally bowed from end to end. Teeth of this type offer numerousimportant advantages over uncrowned teeth, and the field oftheir use isconstantly increasing. -The pres;

ent apparatus provides a convenient means for measuring the crown g'ofgear teeth. This may.

be accomplished by tw methods. It may be done by comparing acrowned-gear tooth with a correspondingly crowned master element I4. Ifpreferred, the master element I4 may be 'provided with. an unmodifiedhelical surface, in

I have indicated in the previously described 23 which case the. desiredcrowning of the teeth of V the work passage I5 would be indicated by apredetermined movement of the pointer on the cora work piece forrotation with said element, ways drawings, the master element isprovided with helical teeth or slots. It will be understood that theapparatus is adapted equally well to measure straight or spur teeth on agear. In this case translation of the carriage 22 will not be accon'i- 5panied by rotation of the master element l4, but any departure fromparallelism in the teeth of the ,gear IE will be at once evident from acorresponding movement of the pointer on the indicator in use. It willof course be obvious that in like manner crowning of spur teeth on thework tween than between measuring pointer 3|, and

the surfaces with which it engages. As a result, translation of thecarriage in one direction will measure the surface/ of one tooth, andreverse translation will measure the adjacent surface of the next tooth.This greatly facilitates complete checking of a gear, and is animportant feature of the present apparatus.

I have disclosed the:present apparatus as particularly'useful inmeasuring of gears, but it will be evident that its function is not solimited, and it is therefore intended to cover broadly apparatus adaptedfor measuring orcomparing surfaces.

. While I have illustrated and described several specific embodiments ofmy invention, it will be apparent to those skilled in the art thatvarious additions, modifications, omissions, combinations andsubstitutions may be made which will be within the spirit and scope ofmy invention as defined by the appended claims.

What'I claim as my invention is: a '1. Acomparator comprising a masterelement having a non-axial surface inclined to the axis thereof, meansfor rotatably mounting said element, means for supporting a work pieceto be checked for rotation with said element, a member engaging saidsurface, means for relatively moving said element and member in adirection parallel to the axis of said element to rotate "said elementand said work piece, and movable measuring means operatively associatedwith said work piece and definitely positioned relative to said member Ifor comparing a surface of the work piece with moving said element andmember in a direction parallel to the axis of said element to rotatesaid element and said work piece, and measuring the said surface of themaster element.

2. A comparator comprising a base, a master element having a non-axialsurface inclined to the axis thereof, means for rotatably supportingsaid element on said base, means for supporting on said base parallel tothe axis of said element, a carriage slidable on said ways,.a memberfixed -on said carriage and engaging sag surface, measuring means onsaid carriage eragvely associated with said work piece, and means for;moving said carriage in said ways."

3. A comparator comprising a' base, a master elementhaving a non-axialsurface inclined to the axis thereof, means for rotatably supportingsaid element on said base, means for supporting a work piece forrotation with said element, ways 'on'said base parallel to the axis ofsaid element, a carriage slidable on said ways, a member fixed on saidcarriage and engaging said surface, measuring means on said carriageadjustable toward and from saidmember and operatively associated apinion carried by said carriage thereof, meansfor rotatably with saidwork piece, and means for moving said carriage in said ways.

4. A comparator comprising a base, a master element having a non-axialsurface inclined to the axis'thereof, means for rotatably supporting W5-said element on said base, means for supporting a work piece forrotation with said element, ways on saidvbase parallel to the axis ofsaid element, a carriage slidable on said ways, a member fixed on saidcarriage and engaging said surface, measur ing means on said carriageoperatively associated with said work piece, and means for moving said,carriage in said ways, said measuring means comprising a movable partadapted to engage a surface on said work piece and a device to indicatemovement of said member.

5. A comparator comprising a base, a master,

element having a non-axial surface inclined to the axis thereof, meansfor rotatably supporting said element on said base, means for supportinga work piece for rotation with said element, ways on said base parallelto the axis of said element, a

carriage slidable on said ways, a member fixed on said carriage andengaging said surface, measuring means on said carriage operativelyassociated with saidv work piece, and means for moving said carriage insaid ways, said last named means comprising afixed rack on said base andand meshing with said rack. 1

6. A comparator comprising a master element having a non-axialsurfacminclined to the axismounting said element, means for supporting awork piece to be checked for rotation with said element, a memberengaging said surface, means for relatively moving said element andmember in a direction parallel-to the axis of said element to rotatesaidelement and said work piece, and measuring means operatively associatedwith said work piece anddefinitely positioned relative to said memberfor comparing a surface of'the work piece with I the said surface of themaster element, said measuring means comprising a movable member--adapted to engage a surface on. said work piece and a device to indicatethe extent of movement of said movable member.

7. A comparator comprising a master element having a non-axial surfaceinclined to the axis thereof, means for rotatably mounting said eleberengaging said surface, means for relatively means operativ ly a'sociatedwith said workpiece and movable in h said member for comparing a,

surface of the workpiece with the said surface of the master element,said measuring means comprising a lever adapted to engage a surface onsaid work piece and a device to indicate the extent of movement of saidle'ver.

8. A comparator comprising a master elementhaving a non-axial surfaceinclined to the; axis thereof, means for rotatably mounting saidelement, means for supporting a. work piece to. be

element and said work piece, and measuring means operatively associatedwith said work piece and movable with said member for comparing asurface of the work piece with the said surface 5'0 ment, means forsupporting a work piece to be V checked for rotation with said element,a memof the master element, saidmeasurlng means comprising a bell crank,onearm of said crank adapted to engage a surface of said work piece, anda device for indicating the extent of movement of the other arm of saidcrank.

9. A comparator comprising a master element having a non-axial surfaceinclined to the "axis thereof, means for rotatably mounting saidelement, means for suporting a work piece to'be checked for rotationwith said element, a member engaging said surface, means for relativelymoving said element and member in a direction parallel to the axis ofsaid element to rotate said element and said work piece, and measuringmeans operatively associated with said work piece and movable with saidmember for comparing a surface of the work piece with the said surfaceof the master element, said measuring means com-- prising a bell crank,one arm of said crank adapted to engage a surface of said work piece,anda device for indicating the extent of movement of the other arm ofsaid crank, said measuring means being adjustable about an axisperpendicular to the axis of said work piece to position the axis ofsaid bell crank substantially parallel-to the surface being compared.

10. Means for measuring the inclination of the tooth surface of a' gearcomprising means .for

mounting said gear for rotation, a master element having an inclinedsurface to which the tooth surface is to be compared, said element fixedto said gear for rotation therewith, a carriage mounted for movementparallel to the axis of said gear and element, apair of members on saidcarriage and respectively engaging the said surfaces, one of saidmembers being rigid and engaging the surface of said master element, the

other member being movable, and means for measuring movement ofsaidlas't mentioned element. 1

11. A comparator comprising asupport, a pair of centers adjustabletoward and away from each other to accommodate a pair of elements to becompared, a pedestal adjustable toward and away fromsaid centers acarriage movable on said pedestal parallel to the axis of said centers,a

contact element carriedby said carriage and adapted to engage a surfaceof one of said pair of elements, an indicator support adjustable on saidcarriage toward and away from said contact element, an indicatormounting on said indicator supp'ort a movable measuring pointer carriedby said mounting, and an indicator adapted to be I actuated-by saidmeasuring pointer.

12. A comparator comprising a'support, a pair ofcenters adjustabletoward and away from each .other to accommodate a pair of members hav--ing surfaces to-be compared, a pedestal adjust-' able toward and awayfrom said centers, a' carriage movable .on said pedestal parallel to theaxis of said centers, a contact element carried-by said carriage andadapted to engagea surface of one of said pair of members and'adjustableon said carriage toward. and away from said one member, an indicatorsupport adjustable on said car- ,riage toward and away from said contactelement, an indicator mounting on said indicator support adjustable onsaid support toward and away from said other member, a movable measbringpointer carried bys'aid mounting, and an indicator adapted to beactuated by said meas- 4 uring pointer.

13. In a comparator, a carriage, a contact element on said carriage,ways on said carriage, an indicator support on said carriagemounted insaid ways for adjustment toward and from said contact element, anindicator mounting adjustably carried by said indicator support,clamping means for rigidly retaining said indicator support in adjustedposition on said ways, and for simultaneously rigidly retaining saidindicator mounting in adjusted position in said indicator support.

14. In a comparator, a carriage, a contact element on said carriage,ways on said carriage, an indicator support on said carriage mounted insaid ways for adjustment toward and from said contact element, anindicator mounting adjustably c'aried by said indicator support,clamping means for rigidly retaining said indicator support in adjustedposition on said ways, and for simultaneously rigidly retaining saidindicator mounting in adjusted position in said indicator support,

and yieldable means effective only on release of said clamping means forretaining said indicator mounting against accidental displacement.

15. A comparator comprising-a rotatablemas- 16. A comparator comprisinga'rotatable master element provided with a peripheral slot extendingaxially thereof, said-slot being of tapered crosssection, means formounting said element for rotation, means for supporting a slotted workpiece to be checked for rotation with said element, a member extendinginto the slot of said master element and engageable with either-side ofsaid slot, means for relatively translating said element and member in adirection parallel to the axis of said element, and measuring meanshaving a part extending into'the slot of said work piece, said memberbeing independently adjustable toward and from said element to vary itsclearance in said tapered slot.

1'7. Apparatus for comparing the surface of a work piece with a similarsurface on a. niaster element which comprises means for mounting saidwork piece and master element for rotation in axially spaced relation,said work piece and element being locked together for simultaneousrotation, means mounting a pair of supports spaced apart by the amountof axial spacing of said work piece and master element, a finger rigidlycarried by one of said supports and adapted to engage one of saidsurfaces, a finger movably carried by said other support and adapted toengage said other surface, a measuring device to measure movement ofsaid movable finger, and drive means for relatively moving said firsttwo means in a direction parallel to the axis of rotation of said masterelement and work piece.

WALTER S.-PR.'AEG.

